DE2253445A1 - PROCEDURE AND DEVICE FOR INSPECTING TRANSPARENT CONTAINERS, IN PARTICULAR BEER BOTTLES - Google Patents

Description

The invention relates to a method for testing transparent containers, in particular beer bottles, in which one a light beam from a light source through an optical system lets the container opening enter the container and observes or observes the light scattered out of the light beam. measures.

A large number of fluoroscopic methods are known for testing transparent containers such as bottles. In many cases it is Kellfeld's nematodes, i.e. one or more light-sensitive receivers are located

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• In the beam path of one or more light sources that illuminate the container either in the transverse direction (DT-AS 1 096 641 and 1 164 706, OT-OS 2 100 729) or through the container opening in the longitudinal direction (DT-AS 1 106 521). This means that small foreign bodies or impurities can only be insufficiently detected. Ee iet also admits a method of the type mentioned at the beginning (DT-AS 1 020 812) ₉ which does not work with the dual lighting process but in which radiation is flared into the container through the container opening, which makes the container wall impermeable The radiation reflected on the inner wall of the vessel and exiting through the container opening is used for the measurement. With these methods, too, the differences between the radiation reaching the recipient from the clean container wall and γοη an impurity or infiltration element are too small or insufficiently specific to ensure a reliable range of very small or relatively equally distributed impurities.

In practice, "especially when testing bottles that are to be reused in Breuerelen vat filling stations," it has therefore not been possible to date to carry out a satisfactory and reliable control in a fully automated manner - rather, the control can be used by the human eye »at least in addition to the automatic

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table control · of partial areas of the container, such as the floor or HbIs, are not insured. Before everything with the Control of beer bottles offer the see where transition »yes Bottleneck settling and drying · «shower residues» in particularly delicate problem. Possibly © here after washing Remaining residues cannot be properly recorded using the previously available pressure test and testing device.

'The invention is therefore "AEIE Mfgabe ssiigsnmäe _9" 1st mnrerl & SSIG working wad particular much on kleinst® bsv. feia distributed YeriBsreiBiguiigflm expressions of the gensanten 'kind wad mim ? orrl®lituiig

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dels all areas of the container, especially in the case of beer bottles, the shoulders adjacent to the neck, where often Foam deposits occur, are well recorded and that also small or finely divided impurities give clearly perceptible scattered light phenomena that from the receiver arranged outside the light beam can be easily and reliably detected and discriminated against against the underground. Even the conventional visual detection of impurities can be caused by this type of Illumination can be significantly simplified and the speed increased. But above all, it is suitable for fully automatic defect recording.

The exact position of the intermediate image or focal point, from which the light beam diverges will depend in the individual case on the shape of the container to be tested. Above all in the case of beer bottles with their shoulders sloping towards the neck, it is advantageous if the intermediate image of the The light source is arranged and the LiohtbUndel so limited that the external rays of the light bundle are approximately tangential run to the shoulders of the container neck.

In the known methods in which the container is only illuminated or transilluminated in certain points or areas, the incident light beam and / or the observation beam must generally be used during the measurement be rotated relative to the container, so one after the other

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all container areas are recorded. This turning of the The beam during the measurement is time-consuming, and the known methods are therefore not suitable for Kontrollraesaungen, which with the fast cycle of modern bottle washing and filling systems, the up to 15 bottles per second to process. Should keep pace. In the method according to the invention, in which essentially the entire inner surface of the container is illuminated at the same time, on turning can be dispensed with if, in an advantageous further embodiment of the invention, one proceeds in such a way that one an image of the container is generated with an optical system directed approximately transversely to the direction of the light beam and the Scans illustration with photosensitive elements. The scanning can take place, for example, by placing the container next to and / or on top of one another arranged photocells cd.dgl. maps each of which generates individual signals assigned to the scattered light coming from a certain container area. Preference «·!» · however, the image is scanned line by line.

It is preferable to generate several over the Huh and / or images distributed around the axis of the container and of the light beam and scans or integrally measures them. ·

The method according to the invention is a dark field

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drive f i.e. the recipient (s) are essentially only light aalals originating from impurities, and the background of the signals is very small. To improve the distance of the signal from the ground even further and, for example, to use the procedure for daily or To know foreign light or while the containers are in rapid motion, one preferably proceeds in this way that the light source and / or the device measuring the scattered light is operated with alternating light or pulsed. For example, by choosing a frequency of the light source that differs from the usual mains frequency, when evaluating the scattered light, all components originating from room light sources can be filled out. If you illuminate the one in motion located container with a very short light pulse, then appears on the measuring device, e.g. the screen of the Scanning device, a "Moaentbild" of the container, which «can still be scanned even after the end of the light pulse.

The invention also relates to a device for carrying out the above-mentioned method, which has an optic as a light source for generating a light beam, a support and centering device for the container in such a way that the light beam enters the container opening, and one outside the container opening Llchtbilndels arranged · has measuring device for the light scattered out of the light bundle. Such a pro

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direction is characterized according to the invention in that the optics, the axis of which approximately coincides with the container axis, is a point of intersection of the rays of the light bundle in the area of the container shark or just above it, and that the heating device is arranged approximately abeam the container outside the bundle of light.

The measuring device advantageously has a Optics depicting containers or partial areas of the container and preferably a line-by-line scanning of this image and generating signals corresponding to the light intensity. Establishment on. In particular, the heating device can after Kind of a television camera with a Vidicon tube. A plurality of measuring devices, in particular in one distributed symmetrically about the container axis, are advantageous Arrangement provided.

For the reasons already mentioned, the light source and the device are preferably controlled with alternating light or in pulses. For the stated purpose, e.g. but also work in a narrow spectral range in which the light source emits selectively and the receiver is selectively sensitive. One that is particularly suitable for both cases The light source that is preferred and therefore preferred according to the invention is a laser. Preferably the pulse rate is from the light source and / or measuring device coupled to the cycle of a device feeding and removing the containers.

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A logic signal processing logic is preferably connected to the measuring device or line scanning device, which triggers a warning and / or control signal when a predetermined pulse height, width and / or frequency is exceeded. By setting the response threshold accordingly, the minimum size and / or number of contaminants at which the device should respond can be set.

The device according to the invention is particularly suitable for testing the lateral container walls and in particular the shoulders of the container. Surprisingly, it has also been found you DFSS impurities or foreign bodies on the container base are very well also detected. If, in individual cases, certain areas of the container, such as the edge surrounding the opening, can only be checked for this catfish insufficiently or with undesirably great effort, see below it is easily possible to use the device with another device for checking this area, e.g. the Behälihalses, to combine or to connect such a device upstream or downstream, this device possibly working on the same principle.

An embodiment of the invention is described below explained in more detail with reference to the drawings.

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FIg. 1 shows a principle of the measuring arrangement of FIG seen the side.

Fig. 2 shows a schematic diagram of the measuring arrangement of seen above with a block diagram of the pulse evaluation device.

Fig. 3 shows another embodiment of the measuring arrangement.

According to Fig. 1, one is placed on a support surface 1, e.g. a conveyor belt, parked bottle 2 by means of a light beam illuminated, which emanates from a light source 3 indicated as a lamp, concentrated in a focal point 5 by an optical system indicated as a lens 4, and from at this point it enters the flat opening in a divergent manner. The focal point 5 is a point of intersection for all rays of the light beam and an intermediate image of the light source 3 · It is at the level of the neck 7 of the bottle 2 or something about it, so that the outer boundary rays 6, 6 * des Light beam roughly tangential to the beveled shoulders δ of the bottle run. In this way it is achieved that especially the inner surface of the shoulders 8, where experience has shown Foam deposits form, are well lit and are not in the shadow of the light, as is the case with was mostly the case with the methods previously used. All other areas of the inner wall and the floor are also

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the rays from the light inside the diaper (e.g. 6 ") well-lit at the same time.

They can be found on the illuminated inner surfaces of the Bottle 2 does not contain any foreign bodies or impurities, so no light is scattered out of the bundle of light limited by the rays 6, 6 *. The field of view of an outside of the Lichtbündel3 arranged light-sensitive receiver stays dark. If, on the other hand, there is a foreign body on the inner surface, it can breathe the light so that Θ3 through the transparent wall of bottle 2 to the outside occurs and can be proven there. An example of a detection device is shown in the right part of FIG. It consists of a receiver 10 with a number of superimposed photocells 11, 11 * etc. and Means for imaging the container or its area the photocells, e.g. in the form of an optical system common to all photocells (indicated by the lens 9) or individual ones, Optics assigned to each photocell (as indicated by the on * cell lenses 9 'indicated). The scattered light emanating from a foreign body 12 is focused by the optics onto a photocell 11 * assigned to the corresponding area, so that this emits a signal.

Another preferred embodiment of the detection device is shown in the left part of FIG. It consists of an optical system indicated by a lens 13 and

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an image scanning tube (vidicon tube) 14, in which an anode 15 with conductivity dependent on the exposure intensity is scanned line by line by an electron beam 16. Optics 13 and vidicon tube 14 together form an arrangement which in principle corresponds to a television camera. Scattered light, which originates from impurities 17 on the inner surface of the bottle 2, is focused by the optics 13 onto a certain point of the photo anode 15, and when this point is scanned by the electron beam 16, this results a signal pulse at the output of the Vidicon tube.

In the arrangement shown from above in FIG. 2, 18 is a conveyor belt or some other conveyor device denotes, the bottles 2 successively the measuring point 19 feeds, in which the bottles by means of the light source 3 in the from Fig. 1 apparent manner are illuminated. That from Impurities or foreign bodies emanating · Scattered light are received by four line-scanning receivers 20, 20 * distributed around the measuring point 19, each of which consists of an optical system and a vidicon tube or can consist of another measuring device, e.g. These receivers 20, 20 * are connected to a logic circuit that evaluates the signal pulses, which is only shown schematically in the drawing for the sake of simplicity for receiver 20 * 1st. At an input 21, pulses for synchronizing the line scanning with the cycle of the conveyor 18 are supplied.

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An output 22 of the line-scanning receiver 20 'is connected to a monitor 23 with a picture display tube serving for control and adjustment in order to synchronize its line movement with the receiver 20 *. The actual signal pulses that occur when a contamination or a foreign body is scanned are picked up at the output 23 of the receiver 20 '. These are also sent to the monitor 23 as light / dark signals. In addition, output 23 is connected to a pulse-evaluating logic circuit, which is indicated overall by the dashed box 24. In its simplest form, the logic contains an amplifier 25 and a pulse height decoder 26, so that only pulses which exceed a predetermined, preferably adjustable threshold amplitude appear at the output 27 as control signals. Instead or in addition, further pulse or signal processing elements can be arranged in the logic circuit 24, such as, for example, pulse type discriminators, differentiating elements, integrators, frequency filters and frequency converters.

In the embodiment shown, the logic circuit 24 only detects such »skin parts or foreign bodies, which cause scattered light of a certain minimum intensity. When using a pulse width criminator the extent of the scattering object can also be recorded. Another embodiment can also be a

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nan integrator included. This adds up the total number of impulses emitted by the Vidicon tube, ie there is an integration of the quantity and size of the scattering objects. A subsequent threshold element or a discriminator generates an output signal when the integrated signal exceeds a certain value. It can thus be achieved that bottles with a cloudiness can be rejected. A turbidity may not have any scattering centers whose size or brightness would be sufficient for the device to respond.

Further expansion of the logic circuit 24 can achieve that further criteria, e.g. the slope of the signal pulses (first differentiation) or the curvature of the impulse course (second differentiation) can be used for discrimination · This allows calibration Separate the scattered light according to special features, e.g. from the bottle rim or from external features of the bottle, e.g. embossed letters, scratches or the like. originates. In particular, specific soiling, such as cigarette butts, ashes, Make out egg white or lye residue.

A further expansion of the logic circuit is when using a color vldicon tube by the discrimination according to Color values possible. For example, you can use the bottle or

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the container to be tested against a background with a run certain basic color. This can be used to ensure that the device remains switched off as long as the Vidicon tube never scans the background. The same This effect could also be achieved, for example, by arranging masks in the beam path. Furthermore, by means of a delay element, a possible, through the entry of the bottle rim in the visual field generated by the impulse projection can be suppressed.

The output signal appearing at the output 27 of the logic circuit 24 can be used to trigger an alarm signal and / or to automatically reject the faulty bottle. For example, the output signal can cause a shaft 23 to pivot into the path of the 'bottles on the conveyor 18, so that the bottles to be sorted out are transferred to a branch track Z'j or the like. Such controllable switches for deflecting faulty containers from the conveying flow are known per se, also in other designs, e.g. as rotating drums or the like.

In particular, a laser can be used as the light source 3 for illuminating the container. The wavelength of the light used for measurement can be in the visible or invisible range, but must be obvious Reasons in the permeability range of the material of the container

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ters 2 lie. The laser or "the light source is preferably operated in pulses, the pulse rate preferably being coupled to the pulse rate or the line frequency of the scanning device 20, 20 'and being gradually controlled by the passage of the container; in particular, the pulse duration can be so Select briefly that a "snapshot" of the moving container is generated or measured in practice.

The illumination beam path does not have to be rotationally symmetrical to the axis of the bottle. 3 shows an arrangement in which several containers are illuminated at the same time. A slit-shaped screen 30 in front of an elongated tubular lamp 31, for example, forms the light source, of which an elongated cylindrical lens 32 generates a grainy, interstitial image in the area of the necks of the bottles 33 below. In this case, the beam path forms an elongated light curtain which is delimited by the edge rays 35 and has the shape described in FIG. 1 in cross section, the bottles passing through this curtain in the longitudinal direction (arrow 34). When visually observed in the transverse direction (arrow 36), all impurities appear as bright points of light. An observer can have several bottles in his field of vision at the same time, whereby the speed of the presentation of the bottles can be increased. Of course, the arrangement according to FIG. 3 is only suitable for visual observation, but

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Even for the automatic measurement, when Heßeinrichtungen ■ it Abbildungeoptik of FIG. 1 may be provided. In all of the arrangements described , the use of template-like diaphragms or masks can hide the scattered radiation coming from the container to be observed in each case or its subarea and hold back external light.

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Claims (20)

P.Bt claims 8 Method for testing transparent containers, in particular beer bottles, in which a beam of light is emitted from a Light source via optics through the container opening in lets the container enter and collects the light scattered out of the light beam and measures "thereby g e -kennzeichne t" that you essentially the entire inner surface of the container by means of a diverging Light bundle that emanates from an intermediate image of the light source generated by the optics in the area of the container neck or just above it, illuminates and measures or observes light scattered through the container wall by impurities on the inside of the container. 2. The method according to claim 1 for testing daring containers, characterized in that dl · External rays of the light bundle run approximately tangentially to the shoulders of the container. 3. The method according to claim 1 or 2, characterized in that one nit approximately transversely to Direction of the light bundle, optics, which are directed at the container, and the image with light-sensitive £ 1 « ten scans. - 17 - 409828/0008 4. The method according to claim 3 »characterized in that partial areas of the container are mapped and scattered light coming from each partial area is measured separately. 5. The method according to claim 3 »characterized in that one dl · image or partial areas the figure is scanned line by line. 6. The method according to claim 3 to 5, characterized in that one eehrere, over dl «height · and / or about the axis of the container and the LlehtbUndels distributes · maps generated and this · integral fromalSt or scanned line by line. 7. The method according to one of claims 1 to 5, characterized characterized in that one dl · light source and / or dae the scattered light measuring device with Vechsellioht or operates in pulses. 8. Apparatus for carrying out the method according to claims 1 to 7 "with an optical system with a light source for generating • in ·· light bundles ·, a support and centering device for the container in such a way that the light bundle la · lahllteruffnung enters, and" iner outside of the LlohtbUwlals arranged hatred device door to the ULchtbUnd'l littered out, characterized in that the - 18 - 409828/0008 Optics (4), the axis of which roughly coincides with the container axis, a point of intersection (5) of the rays of the light bundle in the area of the container holse3 (7) or just above it, and that the measuring device (9, 10 or 13 »14 or 20, 20 ') is arranged approximately across the container (2). . 9. Device according to claim 3, characterized g e k s η is characterized in that the measuring device or more, comprising a container or portions thereof imaging optics (9,13). 10. The device according to claim 8, characterized in that the measuring device is assigned to each image and the scattered light contained in it has receiving photoreceptor. 11. The device according to claim 9, characterized in that the measuring device is the image line-by-line scanning and generating signals corresponding to the light intensity (14). 12. The device according to claim 11, characterized in that g e k e η π draws, that the measuring device is designed in the manner of a television kasera with a Vidicon-I tube. 13 * Device according to one of claims 8 to 12, there- - 19 - 409828/0008 characterized in that several measuring devices (20, 20 ') are provided, in particular in an asymmetrical arrangement over the container axis. 14. The device naeh one «of claims θ to 13», characterized in that the light source (3) and Measuring device work in a narrow spectral range. 15 · device according to one of claims 8 to 14, characterized in that the light source and / or Work the measuring device with alternating light at a specific frequency or in a pulsed manner. 16. Device naeh one of claims 8 to 1S _9, characterized in that the light source let a laser. 17 · Device according to claim 15, characterized in that the pulse rate of the light source and / or The measuring device is at the rate of a demand and demand for the container Vorrlehting (18) is coupled. 18. Apparatus according to claim 10 or 11, characterized in that the photo receiver or the Cell Scanning Device has a logic operating logic (24) is connected, which when a predetermined - 20 - 409828/0008 ■. : ■■. <«'■■ _: ■ given pulse height, width and / or frequency a warning « and / or triggering the control signal. 19. Device according to one of claims θ to 18, characterized «in that it is combined with an additional device for testing the container neck or is connected upstream or downstream of such a device. 20. Device according eineis of claims 3 to 18, characterized in 'that? I- ge apertures or masks coma forming Liehtee are arranged between the container and the measuring device, one or more gg h Mtei ^f n ienar1 for shielding the non-rom container. - 21 - 409 8 28/0008